The present invention relates to bumper beam assemblies and methods for making the same.
Open cross-section and closed cross-section bumpers for conventional motor vehicles are known in the prior art. It is also known that either type of bumper can be made by roll-forming or by stamping. Closed cross-section bumpers of a straight configuration can be formed by roll-forming a continuous sheet of metal so that the longitudinal edges thereof abut each other and then seam welding these edges, or by stamping two xe2x80x9cclam-shellxe2x80x9d halves having a C-shaped cross section and seam welding the halves together.
Each type of bumper is frequently also provided with an arcuate curvature in the longitudinal direction. Often this longitudinal curvature, sometimes referred to as the xe2x80x9csweep,xe2x80x9d is imparted to the metal by passing the same through a series of mandrels following a roll-forming operation.
Conventional open cross-section bumpers are disadvantageous in that such bumpers offer less resistance to deformation during impact for a given metal gauge and thickness than a closed cross-section bumper. Conventional open cross-section bumpers are often strengthened by increasing the metal thickness, which results in an undesirable increase in weight and materials cost.
However, open cross-section bumpers are typically easier to manufacture than closed cross-section bumpers. For example, it is easier to roll form and bend an open cross-section bumper to provide for bumper sweep, even when a relatively high tensile strength steel is used to construct the bumper. That is, it is relatively more difficult to provide a straight roll-formed closed cross-section bumper with sweep, because bending a closed cross-section beam tends to cause the metal material to buckle. Consequently there exists a need in the art for a bumper beam assembly that provides the impact strength of a closed section beam without the difficulties typically associated with providing a desired curvature or sweep to the closed section beam.
It is also known in the motor vehicle industry that different vehicles have different strength and size requirements for their associated bumper beams. Conventionally, different tooling would be required to manufacture the different beams for each particular application. However, providing different toolings for each particular application is very expensive and occupies manufacturing space that could be utilized for other purposes. Consequently, there exists a need in the art for method by which a plurality of different bumper beams can be made using a limited set of toolings.
It is an object of the present invention to meet the needs described above. To achieve this object, the present invention provides a modular bumper beam assembly and a method for manufacturing the same which solves many of the above-described technical problems. The bumper beam assembly in accordance with the present invention is formed by: roll forming from sheet metal a plurality of substantially identical elongated bumper beam members each having a generally opened cross-sectional configuration including one opened side, the plurality of bumper beam members including a first set of bumper beam members having a first longitudinal configuration and a second set of bumper beam members having a second longitudinal configuration different from the first longitudinal configuration; stamping from sheet metal a plurality of elongated, generally planar bumper beam mounting structures, and fixing a selected number of bumper beam members from one of the first and second sets of bumper beam members on a selected mounting structure within the plurality of mounting structures such that the selected mounting structure closes the one opened side of each of the selected number of bumper beam members.
In accordance with another aspect of the present invention, there is provided a method of forming a plurality of bumper beam assemblies for accommodating different applications. The method comprises roll forming from sheet metal a plurality of elongated bumper beam members each having a generally identical longitudinal configuration to form an inventory of elongated bumper beam members; stamping from sheet metal a plurality of elongated, generally planar bumper beam mounting structures; selecting a first number of the bumper beam members from the inventory; fixing the first number of bumper beam members to a selected one of the bumper beam mounting structures to form a first bumper beam assembly; selecting a second number of bumper beam members different from the first number; and fixing the second number of bumper beam members to another selected one of the bumper beam mounting structures to form a second bumper beam assembly different from the first bumper beam assembly.
As described in detail hereinbelow, this manufacturing method offers numerous advantages. The bumper beam member is provided with an open cross-section during the roll-forming process, and thus it is easier to bend the bumper beam member longitudinally in order to provide the desired degree of arcuate curvature, or sweep, in comparison to bending a structure with a closed cross-section.
The closed section is formed from two parts, and therefore higher strength steel can be used to construct the bumper beam member in comparison with the mounting structure portion of the closed section.
In a preferred embodiment, the bumper beam members can be nested to provide increased bumper strength.
In accordance with another feature of the present invention, bumper beam mounting structures can also be constructed in different sizes to accommodate a selected number of bumper beam members.
In accordance with another feature of the present invention, bumper beam mounting structures may be secured together prior to fixing the bumper beam members thereto in order to form larger bumper beam assemblies.
Also in accordance with the invention, a plurality of identical bumper beam members and bumper beam mounting structures can be easily stored and maintained in an inventory to construct a wide range of bumper beam assemblies as needed.
Other objects, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims.